Because Brook saves lives more than people realise.
His lungs didn't need air anymore. A few seconds ago that had seemed the most important thing in the world, aside from saving his hammer nakama, but now it seemed trivial. With an innocent detachment he saw the last few bubbles leave him. His body swirled around weightlessly in the raging seawater, but the rope around his waist kept pulling him back. His arms never let go of the dead weight in his cramped arms. The blue water stung their salt in his blue eyes, but he wasn't in power to close them. He only saw the dark blurring his vision and then he saw nothing.
Haven't heard from you in a long time. Had a nice life?
He heard a voice, sweet as honey and flowers and beauty, a whisper of a warm breeze across his face. He wanted to answer how his life was a lot better now that she was here. She giggled and he was happy the girl was happy. He just couldn't move.
You know you won't die like this, the sweet voice stated sadly. The sudden change of tone was confusing, like he was missing out on something, but that might as well be true: this wasn't the only voice that spoke to him. Outside of his focus on her he heard other voices, rapidly whispering in languages he didn't understand, and now he wished he hadn't focused on them because they became louder and louder and pulling and cutting into his ears like sharp hail on his skin, tearing off his nerves and leaving him tingling and numb. He struggled but still couldn't move and felt himself panicking.
I'm not able to kill you right now, she soothed him and the heat tried to curl around him, saving him from the icy knives outside of her presence. He clung onto her with all his mind power –as his body couldn't- and she returned the hug, making him feel so much better suddenly. No more painful voices. He calmed down, felt himself forget, let the heat and warmth and comfort and searing happiness course through him, before she pushed him away sadly, like she wanted him two but knew they couldn't be together. He still felt her as if she held him on an arm length of distance.
When you really want to die, make sure you have nothing to return to.
And then the heat disappeared completely, the cold bones in his arms continuingly tugging them into the deep, the lifeline a forgotten escape to the surface. In this numbing cold he felt his mind drifting away into blackness and oblivion, his body floating in the storm lifelessly, but his thoughts didn't evaporate before a flash of a smile entered his mind; the captain and the crew and the ship that he wanted to go home to.
/
Two bodies floated lifeless in the water, one unconscious, the other paralyzed by the power of the sea. Soon the others would realise this and pull in the lifeline, pull them back aboard the ship. Luckily he didn't need to breath, couldn't die though Death longed after him from a distance like a shy girl longs after her first crush, the kind of guy that's way out of her league. She couldn't see past him and would not see the dying gentleman that held him and whom she'd originally been summoned for.
When he himself was ready to die, after seeing Laboon again, after Luffy had lived his dreams and his nakama had passed away, he'd embrace the warmth of her waiting arms.
He'd burn his bones until nothing was left.
...
AN: First published fanfic, yeay~
This is my head canon for Brook's powers, part of the reason I think noone of the crew ever really dies (besides 'for happiness' sake') It disregards the time he wasn't part of the crew yet, but maybe their fate was already aware of him. Or something.
I've been told this is a rather subtle piece, but it's basicly Brook keeping Death distracted from Sanji, who is drowning after trying to save the skeleton, and Sanji hears Death talking (to Brook, but he doesn't realise that). However, interpret it as you want.
